A conventional over voltage protection device is installed near I/O ports on a printed circuit board to protect internal IC devices according to demands by each IC device. However, such design requires installing independent over voltage protection devices in accordance with requirements of respective circuits to prevent respective IC devices from being damaged by surge pulses.
Please refer to FIG. 1a, which is a top view of an IC device disposed on a conventional substrate. In FIG. 1a, there are a plurality of electrodes (11) and a grounding line (13) disposed on a substrate (12). Then, an IC device (10) is soldered to the plurality of electrodes and the grounding line. FIG. 1b is a sectional view of the IC device disposed on the conventional substrate. In FIG. 1b, we can understand the relationship among the constituent elements. Because such structure cannot provide over voltage protection functions, the IC device cannot withstand the energy of surge pulses, which result in irrecoverable damage to the IC device.
In order to protect the IC device, several over voltage protection devices are frequently proposed. However, those over voltage protection devices need to install individual protection devices on a printed circuit board according to actual demands after the IC device is manufactured and installed near the I/O ports on the printed circuit board. Therefore such a design has the disadvantages of high design costs, wastage of limited space, and incomplete protection for the IC device.
Therefore, there is a need to provide an IC substrate with over voltage protection functions. In this substrate, a plurality of over voltage protection devices is provided simultaneously to solve the problems of the prior arts that are unable to provide the over voltage protection or to eliminate the inconvenience in the prior arts of installing individual protection devices on a printed circuit board. The present invention provides an IC substrate with over voltage protection functions to eliminate such inconveniences.